Polymerase chain reaction (PCR) is a method for the rapid and exponential amplification of target nucleic acid sequences. It has found numerous applications in gene characterization and molecular cloning technologies including the direct sequencing of PCR amplified DNA, the determination of allelic variation, and the detection of infectious and genetic disease disorders. Various thermostable DNA polymerases have been used for PCR applications; for example, Taq polymerase isolated from Therms aquaticus (Taq), pfu polymerase derived from Pyrococcus furiosus, KOD polymerase isolated from Thermococcus kodakaraensis, and Vent™ DNA polymerase isolated from Thermococcus litoralis (Tli). See, for example, U.S. Pat. Nos. 6,008,025, 5,545,552 and 5,489,523, each of which is incorporated by reference in its entirety.